In case of designing a lead frame for a semiconductor device so as to decrease kinds of lead frames, the structure of a semiconductor chip is basically adjusted in the design of the semiconductor chip so that the chip can be mounted on an existing lead frame. However, there is a case that the chip cannot be mounted on the existing lead frame, when one chip is applied to a few packages or when there is a product constraint.
When the chip is mounted above the existing lead frame and a wire bonding step is carried out, there is a risk that a wire interval becomes very narrow in a specific portion so that adjacent wires contact each other to form a short circuit, if the mount position of the chip is shifted or the wires are eccentrically-located. For this reason, the structure of the lead frame needs to be deformed.
As related techniques, Patent Literature 1 (JP H04-80931A) discloses a semiconductor device in which a tab suspension lead is deformed into an arrangement direction of inner leads.